Samsung 840 Pro and Over Provisioning

Discussion in 'MacBook Pro' started by Doc69, Jan 8, 2013.

  1. Doc69 macrumors 6502

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    Dec 21, 2005
    #1
    I just bought a Samsung 840 Pro SSD. I hooked it up to a PC and updated the firmware with the SSD Magician software. I now see that the Magician software has a section called "Over Provisioning". Do I need to do anything here before moving the SSD to my Mac?

    My old OWC SSDs all have built in over provisioning. Since the Samsung drive apparently does not come with it out of the box, do I need to set this up on my PC before moving it to my Mac, or what's the deal here.

    Also, should I enable Trim on my Mac or not?
     
  2. w00t951 macrumors 68000

    w00t951

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    #2
    Just boot to the install disk, go to Disk Utility, and Erase the disk as Mac OS Extended (Journaled). OS X doesn't need any partitions made by Samsung's software.

    And yes, do that. While it's likely slightly redundant as many modern SSDs already have TRIM commands built into the memory controller, it doesn't hurt to have the OS issue TRIM commands once in a while. Besides, Samsung drives don't garbage collect on the go - it only occurs when the machine has been idle for a few hours.
     
  3. Doc69 thread starter macrumors 6502

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    #3
    If the Samsung drive doesn't need an extra partition for over provisioning, then why does many other SSDs have this built in? I thought an over provisioning partition was needed for garage collection to work properly. But are you're saying that the garbage collection does not work well on Samsung drives anyway and that no over provisioning partition is necessary?

    It's very confusing, but perhaps I don't need to concern myself about these details? I just want the drive to work as fast and efficiently as possible.
     
  4. SDAVE macrumors 68040

    SDAVE

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    #4
    You're thinking too much.

    Just check if there is a firmware update, that's it.

    If no firmware updates (most likely not, Samsung doesn't update that often) then shut down your PC and take out the SSD and put it in your MBP.

    After you set it up (fresh install or a copy) download Trim Enabler and enable trim.

    Off you go, enjoy.
     
  5. w00t951 macrumors 68000

    w00t951

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    #5
    Just erase and install. That's what I've done on every SSD machine, Windows and Mac OS. It's probably some drive recovery software that doesn't support uEFI boot in the first place, so it's useless.

    Garbage collection is handled by the memory controller and is initiated by TRIM commands, which can be automated by the SSD or manually issued by the OS.
     
  6. ScoobyMcDoo macrumors 65816

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    Austin, TX
    #6
    I just ordered one of these and do plan to set up 7% over provisioning. I read a article somewhere that they did show better performance with over provisioning set up.
     
  7. paul-n macrumors regular

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    Jul 12, 2012
    #7
    All SSD have overprovsioning. Samsung 840 Pro is sold with 256,000,000,000 Bytes space, but there are 256 GiBi build in which are 274,877,906,944 Bytes. There are 7% internal overprovisioning and there is no need to do overprovisioning. The Samsung tool only creates a partition which is smaller then the total size.
    I would just use the SSD as a hard drive and try to keep at least 10% free or more.
     
  8. xxjudgmentxx macrumors member

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    #8
  9. richnyc macrumors regular

    richnyc

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    #9
  10. theluggage macrumors 68030

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    Jul 29, 2011
    #10
    So... that seems very clear that it is worth either setting 10%+ over-provisioning in firmware, just making your partition a tad smaller than the disc (or, presumably, just not letting your disc fill up).

    However does anybody know what happens if you create a DIY 'Fusion' drive (as described in various places on teh interwebs)? I'd guess that the firmware or undersized-partition would still work, but is Fusion smart enough on its own to not completely fill the SSD? If so, overprovisioning on top of that would just waste valuable bits.

    (Just got shiny new Samsung 840 pro for my 17" MBP and waiting for my opitbay to arrive).
     
  11. xxjudgmentxx macrumors member

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    #11
    No problem. It's a good read for everyone with an SSD or two.

    I think you need to at least partition it and leave one part as free space or use OP through Samsung's software to get the most benefit. Leaving the whole drive as a single partition but not filling it is different than deliberately leaving a portion of the drive marked as 'inactive' for the SSD's firmware to take advantage of. In any case, not filling the drive is better than nothing.

    Not sure on Fusion Drive setup. Haven't much looked into that. Maybe someone else can comment? It would depend on how you setup the SSD for it and if creating the fused drive reformats the whole SSD then it'd be useless.

    Congrats on the 840. I have two in my MBP (one for OS X, one for Windows/games) and they're fantastic. Glad I saved money over the Pro models for sure (partitioned the 250 as 200GB and 50GB free space, 500GB is partitioned as 400GB with the remaining 100GB blank as well).
     
  12. matamoris macrumors regular

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    Sep 3, 2011
    #12
    Ars confirmed that Fusion will keep 4GB free on the SSD. If you copy a enough data to your Fusion drive that it overflows to your spinny disk, the OS will shuffle 4GB of data off the Fusion on the spinny drive. So, the system tries to keep some free space on the SSD. I don't know if this is for SSD perf reasons or to ensure that there is always room for writes on the SSD.
     
  13. matamoris macrumors regular

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    Sep 3, 2011
    #13
    A follow-up on this: my 840 Pro performed terribly in a Fusion configuration when I included the entire disk in the primary partition (100% usable space). Presumably, this (even with the 4GB reserve maintained by CoreStorage) does not leave enough room for garbage collection / trim to work effectively. I rebuilt the FD with an SSD partition that was 85% of the total size, and performance is now in the 500mb/s for both reads and writes.
     

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